Vending machines are used as an outlet for retail goods, including packaged foods, desserts, candies, soft drinks, toys, and stamps and to wash and dry clothing. An operator of vending machines may have a hundred or more machines under his or her control, each of which must be routinely visited to supply inventory, remove cash, and verify that the machine is in good operating condition. Between such visits, however, the machine is accessible to the public, including thieves.
Existing machines consist of an enclosure with the forward surface of which openable as a door for replenishing the magazines with goods and for removing cash. A hook retains the door in the closed position and is openable using a key. Although the enclosures and locks for such machines are constructed to discourage unauthorized entry, a professional thief will study the construction of such enclosures and locks and find the weakest portion of their construction, which is usually at the lock. A professional thief, having knowledge of the weaknesses of a vending machine and carrying proper tools, can defeat the lock of an existing vending machine and access its magazine and cash box within seconds.
A sturdy locking device is needed to retain the door of the vending machine cabinet closed. Currently, two structures are in use for locking such cabinets. The first structure consists of a screw mounted on the door or the frame of the enclosure and a complementary nut on the other member, with the screw tightened or untightened into the nut to lock or unlock the door. The screw may be manually or electrically rotated, however, one disadvantage of manually operated screws is that the location of the handle to turn the screw is readily visible from the exterior of the cabinet.
The alternative method for latching a vending machine cabinet includes an upwardly directed, rigidly mounted hook positioned on either the door or the cabinet and a vertically moveable latch bar on the other member. The latch bar has a plate that is lifted and moved behind the hook and lowered to latch the door. One advantage of the latch bar is that the bar can engage a plurality of hooks spaced along its length, and the locations of the hooks cannot be determined without opening the enclosure. A disadvantage of the latch bar is that the latch bar must be lifted from a lower position to its upper position by turning a lever arm each time the door is either opened or closed.
With the advent of handheld electronic transmitters and the like, it has become increasingly popular to hide an electronic receiver in the exterior of a cabinet for receiving a signal from an electronic key to open the door of a vending machine. When the door is latched closed with a slide bar, the electronics within the machine include the concealed detector for receiving an electronic signal, a microprocessor containing logic in which the signal received is compared to a code stored in memory. If the signal received matches the code in the memory, the electronics of the machine will energize a solenoid to raise the slide bar thereby lifting the latch plate from behind the hooks that retain the door closed. Such machines normally retain the slide bar in the elevated position for a fixed period of time after which the solenoid is de-energized and the slide bar is allowed to drop to its lower position.
When a technician services a vending machine, the door will be open for several minutes while the magazines of the machine are refilled and the cash in the coin box removed. The technician may also undertake minor repairs to the equipment of the machine and verify that its components operate properly. The timing device of the machine, which controls the operation of the solenoid, maintains the solenoid in the open position for a very short period of time to minimize the risk of unauthorized invasion into the cabinet. Accordingly, the slide bar is usually dropped by the solenoid to its lower position long before the technician is ready to close the cabinet, and therefore the slide bar must again be lifted until the door has been closed and the latch plate again positioned behind the hooks.
Where a vending machine cabinet is provided with a slide bar that is electronically operated, the slide bar includes a mechanical backup for operating the slide bar and unlatching the door in the event of the failure of the electronics that operate the solenoid. The location of the mechanical backup, however, is concealed so it is not readily accessible to thieves. The mechanical backup requires a template to locate a point at which a hole can be drilled in the machine through which a tool can be inserted to mechanically lift the slide bar. A vending machine cabinet fitted with a slide bar-type latch, therefore, can only be closed by either operating the electronic transmitter for a second time as the door is closed, or by providing a mechanical structure which will engage the slide bar and raise the slide bar over the hook as the door is moved from an ajar position to a closed position.
The technicians that service vending machines are often employed by a service agency or by the owner of the machine who wish to retain a degree of supervision over the activities of the technician. The electronics in the machine and in the handheld key may therefore include one or more programs to monitor the amount of cash received into the cash box between services dates of the machine. Where this is done, it is also desirable that the machine be capable of distinguishing between a latching and an unlatching event. To simplify this distinction, it is preferable that the cabinet door of a vending machine having a slide bar-type latch includes a mechanical method for raising the slide bar as the door is closed so that a subsequent actuation of the solenoid is not required. One obvious method of providing a mechanical means for raising the slide bar is to provide a ramp surface that extends outward of the hook that will engage a lower edge of an opening in the slide bar. As the door of the cabinet is closed, the slide bar will be lifted by the ramp surface until the latch plate can fall behind the hook. The problem with this structure is that it requires that a rigid tapered member extend outward of either the door or the enclosure, which may cause injury to a technician or to an innocent bystander. It would be desirable, therefore, to provide a mechanical means for lifting the slide bar that does not rely upon a rigid ramp surface.